1969 Chevy Camaro - Floor Creation & Mini-Tubs

Part 3: Jigsaw Puzzle

In the last two months, we've followed along as Auto Metal Direct's Installation Center stripped our 1969 Camaro from a complete roller to a bare skeletal frame of rockers, A-pillars, C-pillars, and some inner roof braces. Once the bones were picked clean, they started rebuilding the carcass with reproduction panels, just like GM originally assembled the unibody platform nearly 45 years ago. (Cue the opening monologue to The Six Million Dollar Man.)

The question always comes up: "Why rebuild the body to this degree, when you could order a replacement body and swap VINs?" We asked Craig Hopkins, head guy at the AMD Installation Center, and learned there are a couple of answers. First and foremost, "It's a real car." What's that mean, exactly? It means the car has legally had the VIN number moved from a rusted, rotted, or accident-damaged piece of sheetmetal, and it has been transferred to a replacement panel required to repair the damaged area. Removing the VIN from one body and attaching it to another body is illegal, but moving it in the process of a repair due to rust or accident damage is not. Now, we'll be the first to admit this is a gray area—to us it's like George Washington's Axe: It's George's Original Axe sitting there in the museum, and in 250 years it's only had the handle replaced three times and the head replaced twice.

But, the law is the law, and it not only varies from Federal to State, but it also varies from state to state as far as titles and registration are concerned because a complete reproduction body assembly, ordered and shipped from a company, starts getting into the kit car area, and some states are much harder to register kit cars than others.

The other important point is that the reproduction bodies are made from 100 percent reproduction sheetmetal panels. And while we're grateful for the repro panel industry, we all have to admit the fit and finish isn't exactly like the original in most cases. This isn't the kind of thing we like to talk about in the magazine business, but everyone in the hobby knows we've all had to tweak, bend, cut, or modify reproduction panels to get them to bolt into place. It's not a problem if you're dealing with a fender, or a quarter-panel, or a rocker panel, or any other individual piece going onto a body—but when you're building an entire, 100 percent reproduction body, you run the risk of multiplying tolerance and fitment issues … it's like making a photocopy of a photocopy of a photocopy. The third-generation copy won't have nearly the resolution (tolerances) as a copy made of the original.

It's very rare that at least some parts of an original body can't be used, while the critical dimensions of what's left of an original body can almost always be used even if the panels are rotted to oblivion: rocker panel length and measurements from original body reference points, doorjambs, door opening dimensions, relationships from package trays and rear seat bulkheads, dash to A-pillar dimensions, original firewall mounting and reference points to rear framerail mounting and reference points, and front leaf-spring mounting points, to name several examples.

Adding reproduction panels to what's left of an original body—or its mounting and reference points—will yield a foundation more like the one GM originally built.

This month we watched the guys at AMD create a floorpan assembly (with mini-tubs), and join the whole thing to the body's skeleton they rebuilt last month. Next month they'll button up the body with external sheetmetal.

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1. There are two main subassemblies that go into making a body: the roof/rockers/firewall and the floor. The AMD Installation Center builds both on jig fixtures, basically the same way GM built them back in 1967-69.

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2. The rear subframe rails are the foundation for the floor system. Note the front spring hanger is in place here as well.

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3. The rear rails are secured to the jig fixture, and the trunk pan is clamped to it and welded in place. The complete rail gets spot-welded to the floor, just like the original …

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10. Here you can see the floorpan sections are bolted to the jig at several points, just like it originally was when Chevrolet assembled them.

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4. ...while the inboard flange of the framerail is plug-welded. Though difficult to see here, at the forward portion of the trunk pan assembly, where it kicks up over the rear axlehousing, there are two layers of panels where it connects with the framerail, forming a boxlike structure. The floors come assembled with the shock mounts already built in, leaving no access for the spot welder; the only option is to plug weld. The spot welder will weld multiple layers, but they have to be laid one on top of the other.

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5. With the rear rails and trunk floor in place, the front floorpan section is lifted over the firewall (which is actually part of the jig, and will not be moved into the body) and secured to the jig.

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6. This is why the leaf-spring mount was attached to the framerail—it helps locate the passenger compartment floorpan.

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7. The floorpans are clamped together along their mating seam, and the passenger compartment pan is clamped to the front portion of the framerails.

9. After the pans and rails were welded together, the floor assembly was built as built by Chevrolet. At this point, they started the installation of Chris Alston’s Chassisworks mini-tub kit. The floors were marked where the new, wider tub goes in.

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11. From the bottom of the car, you can see the added clearance afforded by the Chris Alston’s Chassisworks mini-tubs (top, or driver side) versus the stock wheel opening (bottom, passenger side). It’s several inches of added tire clearance.

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12. With the wheeltub area clearanced, the complete floorpan assembly is ready to be mated to our body.

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13. The floorpan is slid into the body from the rear, and affixed to mounting points on the body jig. Remember, the body already has the firewall assembly on it, while the firewall on the floor jig stays with the jig.

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19. The inner wheelhousing is clamped to the framerail and seat bulkhead, the floor drops are clamped to the inner wheelhousing and trunk floor, and the trunk floor is clamped to the inner valance, which is clamped to the end of the framerails. Remember, the whole floorpan assembly is bolted to the body jig. The reason for clamping everything in place, rather than welding one piece at a time, is to correct any misalignments and trim excess metal if and where needed. Once everything is fitted together, the welding will begin.

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20. The outer wheelhousing is clamped to the inner housing along the factory flange, using the factory alignment hole in the flange.

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14. To clear the wider inner wheel housings/mini-tubs, the bulkhead area behind the rear seat is trimmed. There are a couple of panels in this area—the bracing from the package tray to the floor, and then a side piece from the bracing to each wheeltub. The spot welds were drilled and a horizontal cut freed the piece that attaches to the wheelhousing.

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15. The wider inner wheelhousing cuts into the framerail—boxing plates are added to maintain the ’rail’s integrity. A note for racers: All reproduction rear ’rails are made to convertible specs, meaning its a heavier gauge and adds a significant amount of structural rigidity.

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21. Once all the clamps are in place, the rear panels of the body are bolted to the jig, the front of the floorpan is clamped to the bottom of the firewall, which is attached to the rockers and the body, which are bolted to the jig. Next month we’ll watch as the AMD Installation Center hangs and fits the outer sheetmetal, and welds it all into a restored body.

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16. With the inner wheelhouse clamped in place, that piece of excess material removed earlier is trimmed and fitted to the new, wider wheeltub, and welded back to the rear seat bulkhead.

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17. At the very back of the trunk floor, the cross rail is fitted to the trunk floor and the back edge of the framerails. It’s just fitted at this point, not welded.

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18. With the cross rail clamped in place, the trunk floor drops and extensions are trimmed and fitted to both sides of the trunk floor, and tied into the inner wheelhousing.